Charge pump, DC-DC converter, and method thereof

Abstract

A charge pump for a DC-DC converter includes an input terminal receiving an input voltage, an output terminal outputting an output voltage, a plurality of charge pumping stages connected in series between the input terminal and the output terminal, and a voltage level shifter shifting voltage levels of first and second gate clock signals so that received first and second gate clock signals have a predetermined amplitude. Therefore, the charge pump can increase power efficiency by maximizing a magnitude of VGS. A DC-DC converter using the charge pump can also be applied to a portable device, for minimizing power consumption, and a method for improving power efficiency of the DC-DC converter is provided.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2005-0044960, filed on May 27, 2005, and all the benefits accruing therefrom under 35 U.S.C. §119, and the contents of which in its entirety are herein incorporated by reference. BACKGROUND OF THE INVENTION [0002] (a) Field of the Invention [0003] The present invention relates to a charge pump, a DC-DC converter, and a method thereof. More particularly, the present invention relates to a high efficiency charge pump, a DC-DC converter including the charge pump, and a method of improving power efficiency of the DC-DC converter. [0004] (b) Description of the Related Art [0005] A digital circuit within a driving chip of a flat panel display is a low voltage circuit that operates with a voltage of about 3V, which is a supply voltage of a chip. However, an analog output stage of a scan driving circuit and a data driving circuit for driving a panel of an organic light emitting device (“OLED”) is composed of a high ...

AI Technical Summary

Benefits of technology

The present invention provides a high efficiency charge pump that can minimize power loss of a charge transfer transistor within the charge pump. This results in a low power DC-DC converter that can be used in a display device that uses an organic light emitting device (“OLED”). The charge pump includes a voltage level shifter that shifts voltage levels of first and second gate clock signals so that received first and second gate clock signals have a predetermined amplitude. Each charge pumping stage includes a charge transfer transistor and a swing transistor, and a maximum value of a voltage applied to the first gate terminal of the charge transfer transistor drops to a minimum value when the first gate clock signal is inverted. The DC-DC converter includes a charge pump and a signal generator generating the first and second pumping clock signals and the first and second gate clock signals. The charge pump includes an input terminal, an output terminal, a voltage level shifter, and a plurality of charge pumping stages connected in series between the input and output terminals. The charge transfer transistor and the swing transistor may be PMOS transistors. The voltage level shifter may receive the output voltage from the output terminal.

Problems solved by technology

Specifically, the DC-DC converter requires low-power and high efficiency of design technology because it is used in a portable instrument.

However, when the charge pump type is used, a voltage drop is generated due to a threshold voltage of charge transfer transistors constituting the charge pump.

Accordingly, in a structure in which power consumption is generated and a high voltage and a high current are output, there is a problem that power loss is further increased and thus efficiency is reduced.

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